Gas tube control apparatus



March 13, 1951 c. H. HOEPPNER ETAL 2,544,684

' GAS TUBE CONTROL APPARATUS Filed 'Feb. 27, 1946 UNILATERAL UNILATERAL IMPEDANCE,

UNILATERAL IMPEDANOE CONRAD H. HOE PPNER- CARL HARRISON SMITH JR.

Patented Mar. 13, 1951 UNITED STATES PATENT OFFICE GAS TUBE CONTROL APPARATUS Conrad H. Hoeppner, Washington, D. 0., and Carl Harrison Smith, Jr., Arlington, Va.

Application February 2'7, 1946, Serial No. 650,582

6 Claims.

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) to the trade as thyratrons, ignitrons, and cold cathodetu es. These particular tubes are enough alike intheir basic properties to permit the statement that any type of circuit set up with one of these tubes can also be set up with either one of the others. Each, however, has its own particular operating characteristics which render it more suitable for certain applications than either of the others. For example, the thyratron and the cold cathode gaseous discharge tubes may be used for control circuits to better advantage than the ignitron. Further, the cold cathode tube, where its limited current capacity is not an obstacle, may be employed in such a manner as to require no quiescent anode power or cathode heating power.

It is an object of this invention to provide elec tronic control apparatus employing gaseous discharge tubes.

It is another object of this invention to provide control apparatus requiring a minimum of standby power.

It is another object of this invention to provide control apparatus characterized by a plurality of states any one of which may be terminated by the application of a single signal at a single point of control.

Other objects and features of this invention will become apparent upon a careful consideration of the following detailed description, when taken together with the accompanying drawings in which:

Fig. 1 is the circuit diagram of one embodiment of this invention;

Fig. 2 is illustrative of an element employed in the circuit of Fig. 1; and

Fig. 3 is illustrative of a variant of the element illustrated in Fig. 2.

Among the principles upon which this invention is based are certain of those governing gaseous discharges. One of these principles is that, once a gaseous discharge between two electrodes has been established, the potential between those electrodes required for the support of that discharge i less than that required for its initiation,

- i. e., the discharge supporting potential is lower than the discharge initiating potential. Another of these principles is that the potential required to initiate a discharge is lowered when ionization is present in the gas. Still another is that a gaseous discharge between two electrodes may be extinguished if the potential between those electrodes is depressed below the discharge supporting potential for a long enough interval for deionization to occur and the discharge will remain extinguished even though the potential between the electrodes be subsequently increased above the discharge supporting value (but not attaining the discharge initiating value) For an illustration of the manner in which these principles have been applied in a practical embodiment of this invention, reference is now had to Fig. 1. In this Fig. 1, tubes I, 2, 3, and 4 represent gaseous discharge tubes of the cold cathode type having three electrodes, it being understood that the other gaseous discharge tubes of the same class may be substituted without substantial change in the mode of operation. It is to be further understood that, while one of the three electrodes, typified by control electrode 5 of tube I, is shown as having the grid structure as supplied in certain of such tubes (such as the RCA 1021), this particular structure is not a limiting feature and other cold cathode tubes having a starter-anode control electrode (such as the RCA OA4G) rather than a grid control electrode may be employed. In tubes I, 2, 3, and 4 shown in Fig. 1, full advantage is taken of the glow discharge characteristic of such tubes to the extent that they do not require, in the quiescent state, cathode heating, either direct or indirect.

Further, potential source 6 of power supply I is of such a value that it will support a discharge between the principal discharge electrodes of the tubes, typified by electrodes 8 and 9 of tube I, only if there is ionization present in the tubes. Thus, in the fully quiescent condition of the circuit of Fig. 1, no power is required from power supply Tim the electrodes of tubes I through 4 and a mentioned above, no cathode heating power is required.

Tubes 2, 3, and 4 each has connected to it a,

utilization means responsive to a principal electrode discharge in the form of relays Fl, F2, and F3, respectively. These'relays represent only one form of such utilization means and any other desired means which responds to the flow of current when its associated tube discharges maybe employed. Relays FI, F2, and F3 may each correspond to different functions and any two, or all 65 three in combination, may correspond to still difierent functions. With the three gaseous discharge tubes 2, 3, and 4 each having associated with it a utilization means any combination of which may be energized, the circuit of Fig. 1 may be characterized by any one of a total of seven distinct states in any one of which at least one of the tubes 2, 3, or 4 is discharging. Still an eighth state is defined by the non-dischargeof any of the tubes. While it will be seen that, were tube I to be similarly arranged with a similar utilization means, an increase in possible combinations would result, tube I serves a difierent purposethat of providing a single point of control at which a single signal may be applied when it is desired to terminate the particular state defined by the discharge or non-discharge of tubes 2, 3, and 4. In order to accomplish this purpose, tube I has associated with it a means rendering it capable of supporting only a temporary discharge. Resistor I3 is disposed in series with the two principal electrodes 8 and 9 of tube I and potential source 6. Resistor I3 has been chosen of such a value that it, in combination with tube I, prevents the passage of sufficient current through tube I to maintain the minimum ionization required for a continuous discharge. That potential source 6 is able to support a discharge in tube I even temporarily is made possible by the capacitance associated with resistor I3. This capacitance bypass resistor in potential and is represented in Fig. 1 by capacitor I I, it being understood that this may comprise an actual circuit element or merely distributed capacitance. As soon as capacitor I4 assumes its charge, as it starts to do immediately upon the initiation of a discharge in tube I, potential source 6 is rendered incapable of supporting that discharge.

With reference to the cipal electrode 9 of tube I to corresponding principal electrode I5 of tube 2 via leads I 6 and I1, capacitor I8, unilateral impedance II], and resistor I9 together comprise a means for coupling tube I to tube 2. A similar means including unilateral impedance II couples tube I to tube 3, and a third means of similar arrangement including unilateral impedance I2 couples tube I to tube 4. Since these three means are similar and function in the same manner, it will be understood that a description of the circuit coupling tube I to tube 2 will apply equally to the other two circuits. The circuit referred to contains, in series connection, a non-conductive coupling element. This space coupling in the embodiment shown is provided by capacitor I8 which is capable of communicating a transient change in potential but which is incapable of establishing that change as a permanent condition. Resistor I9 represents a bi-lateral element of high resistance which provides for the return of the unilateral impedance side of capacitor I8 to the potential of lead I6 so as to prevent thereby afloating condition. This resistor I9 may either be an actual circuit element or it may represent the backresistance of certain forms of unilateral impedance I0. As indicated, unilateral impedance I 0 may take any one of several forms, the principal requirement being that it must present a low resistance to electron flow (opposite in sense to conventional current flow) from tube I to tube 2 and a high resistance in the reverse direction. One such form is shown in Fig. 2 to which transitory reference is now had. As there represented, it is a high vacuum diode which is characterized by a low resistance to electron flow from I 3 for abrupt changes cathode IOA to anode I DB and a high resistance in the reverse direction. Its disposition in the coupling circuit of Fig. 1 may be made with cathode IBA directly connected to principal electrode 9 of tube I and anode IIlB connected through space coupling I8 to principal electrode I5 of tube 2. The disadvantage of the high vacuum diode as a unilateral impedance in the circuit of Fig. 1 is the necessity for heating cathode IDA. This introduces a standby power requirement which may be objectionable in certain cases. This requirement may be eliminated by the use of another form of unilateral impedance I I] such as is shown in Fig. 3. With transitory reference to that figure, it will be seen that the symbol for a conventional selenium or copper oxide rectifier is illustrated. Practice has demonstrated that the resistance to electron flow in the sense opposite to the direction in which arrow IIJC is pointing is low enough and high enough in the reverse direction) to serve as a unilateral impedance which endows the circuit of Fig. 1 with a fully responsive condition in which no standby power is required (tubes I through 4 not conducting).

There is associated with each of the tubes I.

2, 3, and 4 a similar means for applying discharge initiating signals individually to the tubes. In

the case of tube I, it being understood that each of the other tubes has a similar arrangement, the circuit comprising terminals 22 and resistor 26 represents a means for applying an electrical impulse, either positive or negative, between principal electrode 8 and control electrode 5. Such circuit connecting prin an impulse signal of proper amplitude initiates a discharge between control electrode 5 and principal electrode 8. This discharge causes the ionization in tube I precedent to the initiation of a principal discharge between electrodes 8 and 9. Thus, a signal at terminals 22, 23, 24 or 25 may be applied to initiate a principal discharge in any particular one of the selected tubes. For the reasons above stated, a discharge initiated in tube I will be only temporary in duration.

In operation, let it be'assumed that the state exists in which none of the tubes is discharging. A signal may then be applied at terminals 24, for example, so as to cause to exist the state characterized by the discharge of tube 3 and the closing of relay F2. A negligible part of the negative surge accompanying this change which appears at principal electrode 2'! of tube 3 will be communicated to lead I6 since unilateral impedance II is so disposed as to present a high resistance to the flow of electrons from tube 3 to tube I. Most of the negative surge will therefore appear as a potential drop across impedance II. A signal may then be applied to terminals 22 so as to initiate a discharge in tube I. The negative surge in potential at electrode 9 of tube I which accompanies this discharge appears in full on lead I6. Since unilateral impedance I I is so disposed as to present a low resistance to the flow of electrons appearing on lead It.

it, while tube 3 "was Ilischarging,--.a 'isignal :had :been applied to terminals 23 sozas toioause tube 2 to discharge and :cause toxex-ist the :state in "which both relay-s F5! .and F2 :are closed, the negative potential fsurge :at electrode of tube 2 would not :have extinguished tube .3 since the uni-lateral action of the means couplin'g tube 2 to tube 1 prevents .any substantial part of the change .from With both tube 2 and 3 discharging, a :signal at terminals '22 will cause both to be extinguished in the manner abov'e'described with respect to the Zmanner in which tube I rendered tube 3 alone incapable of supporting a discharge.

By means of the circuit combination of tubes 2, 3 and 4 may be caused to discharge by selectable application of signals at terminals .23., 24 and 25 and any such combination state may be terminated by application of a signal at terminals 22-. it will be noted that shown in Fig. 1, any

tube 1, having fulfilled its destiny by eXt'i-n'g'lllishing those of tubes 2, 3 and 4 which might be discharging, is itself rendered incapable of supporting a discharge.

Since certain further changes may be made in the foregoing constructions and different embodiments of the invention may be made without departing from the scope thereof, it is intended that all matter shown in the accompanying drawings or set forth in the accompanying specification shall be interpreted as illustrative and not in a limiting sense.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. Control apparatus comprising, a plurality of gaseous discharge tubes, separate coupling means connected between one of said tubes and each of the remaining tubes in said plurality operative responsively to discharge in said one tube to terminate discharge in any remaining conducting tube, separate signal input connections for each of said tubes for applying discharge initiating signals individually to each of said tubes, means renderin said one tube capable of supporting only a temporary discharge, and a plurality of utilization means each coupled to a corresponding one of said remaining tubes and responsive to the discharge thereof.

2. Control apparatus comprising a plurality of gaseous discharge tubes, separate uni-lateral impedance means coupling one of said tubes to each of the remaining tubes in said plurality operative to present a low resistance to electron flow from said one tube to each of said remaining tubes and a high resistance in the reverse direction, separate signal input connections for each of said tubes for applying discharge initiating signals individually to each of said tubes, means rendering said one tube capable of supportin only a temporary discharge, and a plurality of utilization means each coupled to a corresponding one of said remaining tubes and responsive to the discharge thereof.

3. Control apparatus comprising, a plurality of gaseous discharge tubes each having at least two principal discharge electrodes and a control electrode, separate uni-lateral impedance means coupling one principal discharge electrode of one of said tubes to the corresponding principal discharge electrode of each of the remaining tubes in said plurality operative to present a low resistance to electron flow from said electrode of said one tube to said electrode of each of said remaining tubes and a high resistance in the reverse direction, separate signal input connections for each of said tubes for applying discharge initiating signals individually to each of said tubes, means rendering said onetube capable of supporting only a temporary discharge, and a plurality of utilization means each coupled to a corresponding one of said remaining tubes and responsive to the discharge thereof.

4. Control apparatus comprising, a plurality or gaseous discharge tubes each having at least two principal discharge electrodes and a control electrode, a source of potential of a value capable of supporting discharge between the two principal discharge electrodes of "any of said tubes only when ionization exists therein, said two principal discharge electrodes of each of said tubes being connected in series with said source of potential, separate uni-lateral impedance means coupling one principal discharge electrode of one of said tubes to the corresponding principal discharge electrode of each of the remaining tubes in said plurality operative to present a low resistance to electron flow from said electrode of said one tube to said electrode of each of said remaining tubes and a high resistance in the reverse direction, separate signal input connections for each of said tubes coupled to each of said tubes for applying discharge initiating signals between the second of said principal discharge electrodes and the control electrode thereof, means rendering said one tube capable of supporting only a temporary discharge, and a plurality of utilization means each coupled to a corresponding one of said remaining tubes and responsive to the discharge thereof.

5. Control apparatus comprising, a plurality of gaseous discharge tubes of the cold cathode type each having at least two principal discharge electrodes and a control electrode, a source of potential of a value capable of supporting discharge between the two principal discharge electrodes of any of said tubes only when ionization exists therein, said two principal discharge electrodes of each of said tubes being connected in series with said source of potential, separate impedance means coupling one principal discharge electrode of one of said tubes to the corresponding principal discharge electrode of each of the remaining tubes in said plurality operative responsively to discharge in said one tube to terminate discharge in any remaining conducting tube, said impedance means each comprising a uni-lateral element in series with a space coupling element, said uni-lateral element being operative to present a low resistance to electron flow from said electrode of said one tube to said electrode of each of said remaining tubes and a high resistance in the reverse direction, separate signal input connections coupled to each of said tubes for applying discharge initiating signals between the second of said principal discharge electrodes and the control electrode thereof, means rendering said one tube capable of supporting only a temporary discharge, and a plurality of utilization means each coupled to a corresponding one of said remaining tubes and responsive to the discharge thereof.

6. Control apparatus comprising, a plurality of gaseous discharge tubes of the cold cathode type each having at least two principal discharge electrodes and a control electrode, a source of potential of a value capable of supporting distrodes of any of said tubes only when ionization exists-therein, said two principal discharge electrodes of each of said tubes being connected in series with said source of potential, separate impedance means coupling one principal discharge electrode of one of said tubes to the corresponding principal discharge electrode of each of the remaining tubes in said plurality operative responsively to discharge in said. one tube to terminate discharge in any remaining conducting tube, said impedance means each comprising a high vacuum diode, a'capacitor in series with said diode, and a resistor in parallel with said diode, said high vacuum diode being connected directly in each instance to said one'principal discharge electrode of said one tube and operative to present a low resistance to electron flow from last said electrode to said corresponding electrode of one of said remaining tubes and a high re sistance in the reverse direction, separate signal input connections coupled to each of said tubes for applying discharge initiating signals between 'the second 'of said principal discharge electrodes and the control electrode thereof, impedance 'means connected in series with the two principal discharge electrodes of said one tube and said source of potential rendering said source of potential capable of supporting only a temporary discharge between last said two principal discharge electrodes, and a plurality of utilization means each connected to a corresponding one of said remaining tubes and responsive to the discharge thereof.

CONRAD H. HOEPPNER.

CARL HARRISON SMITH, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

